This invention relates in general to wind turbine towers. In particular, this invention relates to an improved wind turbine tower having a hybrid concrete-composite construction and a method of manufacturing such a hybrid concrete-composite tower.
A variety of conventional wind turbine towers are known, and each has limitations, including the difficulty in erecting towers taller than about 80 m. Tubular steel towers for example, are also typically limited to diameters of about 4.6 m, so that they can be moved by truck. Although towers having hub heights greater than about 80 m have been built, such tall towers are expensive and very difficult to construct and erect using conventional construction methods. For example, the height, diameter, and weight of tubular steel tower sections required for towers taller than about 80 m, are not only difficult to manufacture, but very difficult or impossible to move from a manufacturing location to a tower construction site. Additionally, such tubular steel tower sections would be difficult or impossible to lift into place using conventional cranes at heights of 80 m and greater.
Other conventional types of wind turbine towers include space frame or lattice towers, also typically formed from steel, post-tensioned concrete towers, typically assembled from panels, and hybrid steel-concrete towers, although each has disadvantages. A lattice tower requires re-tightening of fasteners throughout its life, is very labor intensive to erect, creates an undesirable perch for birds, and is difficult to climb. The panels of a post-tensioned concrete tower are very heavy and require a heavy crane to erect. And the sections of a hybrid steel-concrete tower are labor intensive to cast or manufacture, and are also very heavy and require a heavy crane to erect.
Therefore, there remains a need to provide an improved wind turbine tower that is lightweight, durable, capable of being erected to heights greater than conventional wind turbine towers, and an improved method of manufacturing such a tower.